Contour-interpolator.



J. R. VAN DUYNE. GONTOUR INTERPOLATOR.

APPLIUATION HLED JAN. 2o, 1910.

Patented Mar. 7, 1911.

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JOI-IN RALPH VAN DUYNE, 0F WHITE PLAINS, NEW YORK.

CONTOUR-INTERPOLATOR.

Specification of Letters Patent.

Patented Mar. 7, 1911.

Application led'January 20, 1910. Serial No. 539,057.

To all whom it may concern.'

Be it known that l, JOHN RALPH VAN DUrNn, a citizen of the United States, and a resident of lVhite Plains, in the county ot' lVestchester and State ot New York, have invented a new and Improved Contour-Interpolator, of which the following is a full, clear, and exact description.

The invention relates to drafting instruments, and its object is to provide a new and improved interpolator, more especially designed to interpolate between two elevations plotted in plan points on any required intervening contours.

For the purpose mentioned, use is made of a base plate having' a. straight edge, an arm intersecting the straight edge` and a carrier capable of moving on the said plate and on which the said arm is mounted.

A practical embodiment of the invention is represented in the accompanying drawings forming a part ot this specification, in which similar cha 'acters of reference indicate corresponding parts in all the views.

Figure l is a plan view of the contour interpolator; Fig. 2 is an under side view ot' the graduated slide; Fig. 3 is an enlarged cross section of the base plate on the line 3 3 1ot Fig. l; and Fig. 4t is a similar view ot the same on the line 4 4 of Fig. l.

The base plate A of the contour interpolator is provided with a straight edge B, pretcrablif' ma de of Celluloid or other transparent or translucent material, and on the upper tace of the base plate A is secured or termed a guideway C. preferably disposed diagonally7 and in which is slidably mounted a graduated slide D, provided along its sides on both faces with graduations D, D2 and D3. D4, as plainly indicated in Figs. 1 and 2, it being understood that the slide can be reversibly placed in the guideway C, to bring either tace ot t-he slide to the top. rlhe graduations represent equal divisions, from zero to 25 on one tace and :trom Zero to 50 on the opposite tace, the graduations D and D2 being in the reverse order, and similarly the graduations D3, D4. Lines C', C2 are placed on the upper end of the guidewav C and are setting lines for the graduations D, D2, D3, D4. On the straight edge B is a starting point B intersected bv the continuation of the lines C, C2, as-will be readily understood by reference to Fig. l.

0n the guideway C is mounted to slide a carrier E, having its front edges E', E2

adapted to indicate on the marks or' the graduations D, D2, D3, D4, and the said carrier E is provided with a spring F, bearing on one side of the guideway C', so as to take up lost motion ol the carrier lil on the guideway C. The carrier E is provided with a lug E3, engaged by a clamping bolt G. on which is mounted to swing an arm H, extending over the tace or' the plate A and intersecting` the straight edge B. The axis oil the clamping bolt G is intersected by the trout edge of the arm H, and the front edges ll, D2, and the axis also extends through a line running parallel with the guideway (l and passing through the starting point B ou the straight edge B. Now when two elerations are given on a chart, inap or the like` and it desired to interpolate between the points, then the plate A placed in position. so that the straight edge B extends from one point to the other with one point at the starting point B. Assume the elevation at the starting point B to be 321.6 and the other given elevation to be 329.4 and let it be required to interpolate for points 328, 326, 32st and 322. Keeping the base plate in the position above stated and using the graduations D2. more the slide D until the point 1.6 tallies with the setting' line C2,

odge E2 tallies with. 9.4, now swing the arm ll attached to the carrier E until its front edge intersects the. given elevation point 329.4, clamp the arm H .tast to the carrier E. so that the arm H moves bodily with the iarrier E. and the interpolator is entirely Set to obtain the required points, now push the carrier E along until the setting edge E2 tallies with Fig. S on the graduations D2, then the intersection ot the ,t'ront edge of the arm H with the straight edge B gives one of the required points which is marked with a lead pencil: in like manner push the carrier E along unt-il the setting edge E2 tallies with Fig. 6 on the graduations D2, and mark intersections as before, and another required point is obtained, and so on, tor points corresponding to Figs. 4 and 2.

The instrument is very simple and durable in construction and can be cheaply manufactured and readily used for accurately interpolating between two elevations.

Having thus described my invention, claim as new a nd desire to secure by Letters Patent:

l. A contour interpolator, comprising a base plate having a straight edge, a graduated scale arranged on the base plate diagonally to the straight edge, a carrier mounted on the base plate to travel over the scale, and an arm pivoted at one end to the Carrier and intersecting the said straight edge.

contour interpolator, comprising a base plate having a marking edge, a Carrier slidable on the base plate diagonally7 to the marking edge thereof, an arm adjustably mounted on the carrier and extending across the marking edge, and a graduated scale slidably mounted on the base plate and over which the Carrier slides.

3. A Contour interpolator, comprising a base plate having a Straight edge and a guideway diagonal to the straight edge, a graduated slide movable in the said guide- \\`ay, ay carrier slidable on the Said guid'eway,

an arm intersecting the said straight edge and pivoted on the Said carrier, and means for vfastening the Said arm in position on the said carrier, to move bodily with the latter.

a. A contour interpolator, comprising a base plate having a straight edge, and a guidetvay extending diagonally of the base plate, a graduated slide in the guideWay, a carrier slidable on the guideway, and an arm pivoted to the carrier and projecting beyond the Straight edge of the base plate.

In testimony whereof I have signed my name to this specification in the presence of tivo subscribing Witnesses.

JGHN RALPH VAN DUYNE.

llflitnesses Cima. l. lVrokoifr, Jr., (hun, E. Hanna Copies of this patent may be obtained for Ve cents each, by addressing the Commissioner of Patents, Washington, D. C. 

